How to diagnose and fix the 3B001 invalid_savepoint_specification error code in Postgres.

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The 3B001 error code in PostgreSQL indicates an “invalid savepoint specification.” This error typically occurs when you attempt to roll back to or release a savepoint that has not been defined or is no longer valid. Here are some scenarios where this error might occur and how you can diagnose and fix it:

  1. Non-Existent Savepoint:
    If you try to roll back to a savepoint that was never created, you’ll encounter this error. To diagnose, ensure that the savepoint was correctly defined before attempting to use it. To fix it, create the savepoint before referencing it.
   -- Create a savepoint
   SAVEPOINT my_savepoint;

   -- Perform some operations

   -- Rollback to the savepoint correctly
   ROLLBACK TO SAVEPOINT my_savepoint;
  1. Previously Released Savepoint:
    Attempting to roll back to a savepoint after it has been released will also result in this error. Once a savepoint is released, it cannot be used again. To fix it, avoid releasing the savepoint if you plan to roll back to it later, or create a new savepoint.
   -- Create a savepoint
   SAVEPOINT my_savepoint;

   -- Release the savepoint when done
   RELEASE SAVEPOINT my_savepoint;

   -- Do not attempt to roll back after releasing, as this will cause an error
  1. Spelling or Casing Mistake:
    Savepoint names are case-sensitive. If there’s a discrepancy in the case or spelling when referencing the savepoint, you’ll get the 3B001 error. To fix it, ensure the savepoint name is referenced with the correct case and spelling.
   -- Create a savepoint with a specific name and case
   SAVEPOINT MySavepoint;

   -- Rollback using the exact same name and case
   ROLLBACK TO SAVEPOINT MySavepoint;
  1. Transaction Already Committed or Rolled Back:
    If the transaction in which the savepoint was created has been committed or rolled back, the savepoint no longer exists. To fix it, you need to ensure that you’re not attempting to use a savepoint after the transaction has ended.
   -- Begin a new transaction
   BEGIN;

   -- Create a savepoint within the transaction
   SAVEPOINT my_savepoint;

   -- Commit the transaction
   COMMIT;

   -- Attempting to rollback now will result in an error because the transaction has ended
   -- ROLLBACK TO SAVEPOINT my_savepoint; -- This will cause an error
  1. Nested Transactions with Savepoints:
    If you’re using nested transactions with savepoints, ensure that you’re rolling back to the correct savepoint in the correct order. Rolling back to an outer transaction’s savepoint within an inner transaction will result in an error.
   -- Begin the outer transaction
   BEGIN;

   -- Create an outer savepoint
   SAVEPOINT outer_savepoint;

   -- Begin the inner transaction
   SAVEPOINT inner_savepoint;

   -- Perform some operations

   -- Rollback to the inner savepoint if needed
   ROLLBACK TO SAVEPOINT inner_savepoint;

   -- Rollback to the outer savepoint if needed
   ROLLBACK TO SAVEPOINT outer_savepoint;

   -- End the outer transaction
   COMMIT;

When diagnosing and fixing the 3B001 error, always ensure that the savepoints are being used correctly within their respective transactions, and that they exist and are valid at the time of the rollback or release operation.

For more information on savepoint usage and error codes, you can refer to the PostgreSQL documentation on error codes and transaction management.

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